Contact structures for electric switches



April 28, 1931. G E JANSSQN 1,802,346

CANTACT STRUCTURE FOR ELECTRIC SWITCHES Filed Sept. 30, 1926 Patented Apr. 28, 1931 UNITED STATES PATENT OFFICE -GUSTAV E.J'ANSSON, OF WOLLASTON', MASSACHUSETTS, ASSIGNOR CONDIT' ELEC- TRICAL MANUFACTURING CORPORATION, OF SOUTH BOSTON, MASSACHUSETTS, A

' CORPORATION OF MASSACHUSETTS CONTACT STRUCTURES FOR ELECTRIC SWITCHES Application filed September 30, 1926. Serial No. 138,751.

This invention relates to contacts for oil immersed electric switches between which the circuit interrupting arc is drawn; and more particularly to the construction of the auxilia contacts whereby the arc will be quid ly extinguished.

The heat of the are drawn between the contacts causes the metal on the contact faces to melt and become volatilized, and the presence of these metallic vapors in the arc stream provides a relatively low resistance path for the are so that it is drawn out and exists for a considerable length of time.

In an oil immersed electric switch, it is highly desirable to extinguish the are as quickly as possible and thereby prevent decomposition of the oil into gases which build up excessive pressure in the switch casing and fre uently result in disastrous explosions. laioreover, the frequency with which the contacts must be renewed is largely dependent upon the severity of the arcs to which they are subjected.

When an arc,is drawn between contacts, only a relatively small area of the contact members is exposed, as the arc is concentrated at a single point. Various attempts have been made to move the point at which the arc occurs across the cool face of the contact member and thus to render the are unstable and also to aid materially in reducing the metallic gases present in the path of the arc and consequently shorten the existence of the are.

It is an object of this invention to provide an improved construction for the arcing contact of a circuit breaker whereby the are drawn upon circuit interruption is continuously'exposed to cool contact surfaces; and more specifically to provide a pa r of cooperating arcing contacts one of which 1s arranged to rotate as the arc is drawn between them.

It is a further object to provide a construction for an arcing contact which will require very littleattention and only at infrequent intervals.

A further object is generally to improve the construction of electric switches.

Fig. 1 is an elevation, partly in section, of

a pair of cooperating contacts embodying the invention arranged in circuit closed posi- Fig. 2 is a cross-section of the contact members on line 2-2 of Fig. 1.

Fig. 3 is a section taken on line 33 of Fig. 2.

As here shown, the oil immersed electric switch embodying the invention includes the stationary contact member 8 which is supported at the lower end of an insulator 10 and is immersed in a bath of oilor other suitable arc-quenching fluid and is connected electrically to a terminal stud 12 of the switch through the interposed conducting block 14. Said stationary contact member includes a number of arcuate segments 16 preferably formed from a ring of conducting material and arranged in an annular group. Four segments are here shown although any desired number may be employed. Each of said segments is secured removably to an electrically conducting supporting arm 18 which in turn is secured dependingly to the periphery of said conducting block 1 1. Said supporting arms are resilient and are arranged to exert a constant pressure against said contact segments and press said segments inwardly. Said segments are adapted to provide both the main and auxiliary contacts of the stationary contact member as is hereinafter described.

The cooperating movable contact member is carried at the upper end of a stud 20, l0- cated approximately coaxial with said insulator 12 and adapted to be moved into and out of engagement with said stationary contact 8 by means of the switch rod 21; and comprises a main contact and an auxiliary or arcing member. Said stud 20 is provided at its upper end with a removable annular screw-threaded tip 26 having an integral annular outstanding flange 28 at its upper end. The external surface of said tip, beneath said flange 28, is arranged to provide a smooth bearing surface on which the auxiliary arcing member is journa-lled.

The main contact of the movable contact member comprises an internally screwthreaded hub received removably on the orarcing member of the movable contact member comprises an integral wheel 36 of conducting material having a peripheral rim 38 which is adapted to provide the movable arcing surface for said auxiliary contact member. Said wheel is provided with a.

plurality of curved spokes 4-0 in the form of turbine vanes so shaped. as to cause said wheel 36 to spin duringthe movement of the switch rod through the surrounding insulat-,

in'gfluid. Said lock nut 41 and said main Contact are adapted to be fixed to said switch:

rod at a point suitably spaced from said flange 28 to allow said wheel 56 to rotate freelyon the bearing 30 of said tip 26.

Said movable contact is adapted to be moved into; and out of said ring shaped stationary contact member and to have the rim of its mainprimary contact 35 held normally in contact with the inner face of said segments 16 as shown in Fig. 1 when the switch is closed. The arcing member is adapted to be close to but preferably free from actual contact with the stationary contact member so that: itis free to rotate when the switch begins to open.

When the contacts are separated under load, the circuit. interrupting arc is first drawn between the rim 35 of the primary movable contacts, and the bottom edge, or arcing face, of the. segments 16 of the stationary contacts but the are immediately passes from said primary members to the arcing ring 38 by reason of the change in effective distance between the two and the stationary contact segments.

As .the. contact supporting stud withits attached contact members moves downward, the primary contacts are first obliged to travel a considerable. distance along the inner surface ofsaid segments 16 before theinterrupting arc is drawn, so that the turbine wheel carrying the. arcing ring 38 will be. rotating rapidly due to its downward movement through the stationary body of oil when or shortly after the arc is transferred thereto from the primary contact tips 35.

By this arrangement the contact surfaces which are in engagement in the normal switch closed position are protected from deterioration due. to the effects of the. arc; and thelower terminal of the arc is transferred to the. moving arcing ring so that it continually acts upon a cool metal surface and rapidly becomes unstable and thereafter extinguished.

The rotation of the arcing member through the cool body of oil serves to maintain the member cool and to prevent the burning thereof.

The construction may be otherwise modified without departing from the spirit of the invention.

I claim:

1 An electric switch having the combination of'two cooperating arcing members .immersediin. oil and hydraulic means operated by the oil to rotate one of said arcing members.

2. An electric switch having the combination of two cooperating separable arcing members immersed in oil and hydraulic means movable through the oil and arranged toprovide a relativerotary movement between said arcing members during the switch-opening 'iovement thereof.

3. An electric switch having the combination of two cooperating separable arcing members and hydraulic means actuated by'the switch-opening movement of said arcing.

members to rotate one of them.

4. An electric switch having the combination of two cooperating arcing members-and hydraulic means to rotate one of said arcing members including turbine vanes arranged in: driving relation with said rotatable arcing member and means to contain a fluid to act upon said turbine vanes.

5. In an oil immersed electric switch, a movable rotary arcing member having an an-. nular arcing surface, turbine blades arranged in driving relation with said member, and means to contain a body of fluid in which said member is movable, said memberand turbine vanes being movable in the fluid in a direction to effect the rotation of said turbine vanes.

6. An electric switch having an enclosing casing adapted to contain oil, a stationary contact member, and a cooperating movable contact member comprising a support, a main contact member fixed to said support, and an arcing member journalled on said support for free rotary movement thereon, and hydraulic meansincluding the oil in the casing operable upon switch opening movement to effect the rotation of said-arcing member prior to the separation of said main contact member.

- 7. An oil-immersed electric switch having a stationa "y contact in inber, and a cooperatingmovable contact member comprising a support, a main contact member fixed to said support-provided with an annular contactincluding the oil surrounding said contact members to impart a rotary movement to sald arcing member upon the initial switch opening movement of saidmovable contact member and prior to the establishment of the circuit interrupt-ing are.

8. An electric switch having a stationary contact member, and a cooperating movable contact member comprising a support, a main contact member fixed to said support provided with an annular contact face, and an arcing member having an annular arcing face and journalled on said support for free rotary movement thereon and hydraulic means to rotate said rotary arcing member.

9. Cooperating separable contact members for an electric switch comprising a stationary conducting ring having an internal contact face, and a contact member movable into and out of said ring, said movable contact member comprising an annular contact member arranged to engage the inner contact face of said ring, and a rotatable annular arcing member disposed in close proximity to said contact member and adjacent to but free from contact with said ring in the closed position of the switch.

10. Cooperating separable contact members for an electric switch comprising a stationary split ring of conducting material having an inner cont-act face, and a movable member adapted to pass into and out of said ring comprising an operating rod, a main contact fixed to said rod and adapted to engage the inner face of said ring, and an arcing member rotatably carried by said rod.

11. In an electric switch, cooperating separable contact members comprising a stationary contact member comprising a plurality of yieldingly supported annularly-arranged segments provided internally with contact faces, and a movable contact member arranged to move into and out of position between said segments and having a main contact member adapted to engage said internal contact faces and a rotatable arcing member adapted to be disposed within but free from said contact faces in the closed position of the switch.

12. A movable contact member for an oil immersed electric switch having a rotatable member, and means including the oil of the switch to impart a spinning movement to said ioember upon movement of said contact mem- 13. A movable arcing member for an electric switch comprising a hub, spokes comprising turbine vanes extended outwardly from said hub, a rim provided with an annular arcing face connected with said vanes, and a conducting support on which said arcing member is rotatable.

14. An arcing member for an electric switch comprising a rotatable member, hydraulic means to rotate said member, a movable support on which said member is journalled and a stationary electrically conducting abutment constituting a part of the conducting path through the switch against which said rotatable member is pressed by the hydraulic action during rotation.

15. In an electric switch, a stationary switch member having an internal annular contact face, and a cooperating switch member movable into and out of said stationary switch member comprising a supporting rod, a. contact member fixed to said rod and having an annular rim adapted for engagement with the internal contact face of said stationary switch member and having spokes connecting said rim with said rod, and an arcing member comprising an annular rim spaced immediately above and having a somewhat smaller diameter than said first rim, a hub journalled freely on said rod, and spokes comprising turbine vanes connecting said hub and second rim, and means to contain a body of fluid in which said switch members are immersed.

16. The method of interrupting an electric circuit which consists in establishing a circuit interrupting are between a stationary contact and a cooperating movable contact, and transferring said are from said movable contact to a rotating arcing cont-act which is associated with .and movable with said movable contact.

17. The method of interrupting an electric circuit which consists in establishing a circuit interrupting arc between a pair of separable contacts, transferring said are from one of said contacts to an arcing member which is in rapid rotation whereby the arc will be exposed to a cold and constantly changing arcing surface.

18. The method of interrupting an electric circuit which consists in drawing a circuit interrupting are between the main stationary and movable contacts of a circuit interrupter, providing said movable contact with an auxiliary arcing member which is adapted to rotate during circuit interruption, and transferring said are from said movable contact to said rotating arcing member whereby the combined eifect of drawing out the arc and subjecting it to cool arcing surfaces will rapidly extinguish it.

19. The method of interrupting an electric circuit which consists in establishing a circuit interrupting are between the two cooperating contacts, and transferring said are from one of said contacts to a rotating auxiliary arcing member which exposes said are constantly to a cool arcing surface.

In testimony whereof, I have signed my name to this specification.

GUSTAV E. JANSSON. 

